A seat air conditioning unit that blows a conditioned air from openings of a seat back toward a hip or back of a person sitting on a seat has been conventionally known. This kind of seat air conditioning unit is for example disclosed in Japanese Patent Publication No. 10-504977 (U.S. Pat. Nos. 5,524,439, 5,626,021, Pat. No. Re. 38,128E). In the seat air conditioning unit disclosed in the above publication, air having passed through a Peltier module is introduced to the openings of the seat back through a duct.
In a seat air conditioning unit, an air ventilation system including such as a blower and a duct for leading a conditioned air to a surface of the seat back is mounted to the seat back. In general, the seat back receives a load (weight) from a person sitting on the seat. To protect such an air ventilation system and improve an appearance of the seat back, the air ventilation system is for example mounted in a space defined between a rear side of a cushion member of the seat back and a back board disposed on the rear side of the seat back.
However, the space between the cushion member and the back board is relatively small. As such, a passage space of the duct is limited. With this, a pressure loss of the air in the duct is likely to increase. Further, the cushion member of the seat back elastically deforms in a rear direction according to the load applied to the seat back. With this, the space between the cushion member and the back board changes. When the duct is deformed or bent with the elastic deformation of the cushion member, the pressure loss in the duct increases. As a result, it is difficult to sufficiently provide a comfortable air feeling to the person.